Hair and scalp leave on treatment compositions comprising various combinations of hair and scalp actives, are known in the art and are commercially available. These compositions may have rheological parameters that optimize the consumer perceived usage experience (spread, coverage, etc.).
Anti-dandruff hair rinse off products are also commercially available. Anti-dandruff shampoos, conditioners, and other rinse off treatments typically incorporate an anti-dandruff active. One type of anti-dandruff agents are particulate, crystalline anti-dandruff agents, such as sulfur, selenium disulfide and heavy metal salts of pyridinethione. Soluble anti-dandruff agents, such as ketoconazole, are also available.
Nevertheless, some consumers desire an anti-dandruff leave on treatment which provides a level of anti-dandruff efficacy that can replace other anti-dandruff rinse off products or be in addition to rinse off anti-dandruff products or provide leave on benefits to hair and scalp that are difficult to achieve with a rinse off product. Consequently, a need exists for a treatment product that combines core anti-dandruff efficacy with additional scalp health and hair benefits that the consumer can notice and feel, i.e. effective, and is delightful to use.
Such an invention should be able to reasonably easily cover the majority of the affected area, such as the scalp, with each application in order to provide the necessary benefit. Such an invention should also be able to remain near the site of application for a reasonable amount of time after application, such that it can deliver the necessary anti-dandruff or scalp benefit actives without dripping, running, or transferring to another location. Finally, such an invention should remain homogeneous across a typical packaging from top to bottom in reasonable environmental conditions so that each application contains and delivers the necessary amount of actives to the affected areas.
For example, one means to achieve excellent coverage of the affected area, such as the scalp, is to deliver actives via a carrier that does not utilize a rheological modifier, or does so in such a way that rheological parameters such as viscosity are low. However, such compositions would not stay where applied and would drip, run, or transfer to other areas in a manner such as to reduce its effectiveness. Thus, it has heretofore been believed that an adequate level of rheological modifier is necessary to retain active(s) in the affected locations as to deliver benefits such as dandruff efficacy and itch relief.
Additionally, such an example as above with no or low rheological modifier would not be able to stably suspend many of the type of anti-dandruff agents that are particulate, crystalline actives, including not exclusively sulfur, selenium disulfide and heavy metal salts of pyridinethione such as ZPT. Thus it has been demonstrated that there is a minimum viscosity at lowstress that is necessary to achieve to homogeneity across reasonable time and temperature conditions such that the first through the last applications are delivering the same active concentration.
Also by way of example, it may then be believed that excellent anti-dandruff stability and retention to application site could be achieved by utilizing a high level of rheological modifiers such that the viscosity at low stress is overly sufficient to stabilize dense particulate actives and prevent dripping, running at application. However, the use of a very high level of rheological modifiers to stably suspend actives such as ZPT can negatively affect the ability of the consumer to effectively and easily manipulate the composition from the application sites to cover the affected area such as the scalp.
It has now been discovered that, surprisingly, a balanced approach to among the composition's viscosity at various stresses must be taken, in addition to the necessary composition of carrier and anti-dandruff active. Both are necessary to maximize the effective and stable delivery of anti-dandruff actives from a leave on treatment to an affected area with normal application. It is an object of the present invention to provide treatment compositions, which provide the above balanced combination of anti-dandruff efficacy, coverage, and active stability. These, and other objects, will become readily apparent from the detailed description below.